Apparatus for connecting a battery plate to a metal strap or post

ABSTRACT

This invention relates to apparatus for connecting a battery plate to a metal strap or post or to moulds therefor. In contrast to existing arrangements lead is fed to the feed passage  17  via an opening  20  which is positioned immediate the ends of the aligned cavities in the set  14  of the mould. This arrangement enables the cavities to be fed with lead at approximately the same time and hence the dip of the lugs into the cavities can be optimised without any significant difficulties. In itself this substantially increases productivity. It has also been found that up to three batteries can be cast simultaneously, particularly if bypasses  16   c  are used for fine tuning the lead supply.

FIELD OF THE INVENTION

This invention relates to apparatus for connecting a battery plate to ametal strap or post or moulds therefore.

BACKGROUND OF THE INVENTION

The term “battery” is used herein to include accumulators. In aconventional lead acid battery it is customary to connect together theplates of each stack by means of a lead strap or post which is fixed toaligned lugs or tabs on the plate. As is explained in detail in WO94/16466, the disclosure of which is incorporated herein, with biggermoulds problems can arise in flowing sufficient lead into the cavitiesin the moulds and the solution postulated in that case was to have apair of these passages for a set of cavities so that one half of the setwas fed from one of the feed passages, whilst another half of the setwas fed from the other, As is discussed in WO 94/16466, this approachhad many advantages and the mould has been extremely successful.

However, problems have arisen in getting consistent post or strapquality, because, as the applicants have now appreciated, that part ofthe set which lies nearest the pump can be filled up to half a secondearlier than the second set of cavities, fed by the other passage, whichare more remote from the pump. As the lugs can only be dipped at asingle instant it is very difficult to optimise the moment of dipping inrelation to cavity fill and this can affect not only the final shape ofstrap or post moulded, but also on the quality, because the thermalexchange that takes place on dipping will vary in dependence on theamount of lead in the mould.

Attempts have been made to solve this problem by very accurateautomisation of the system, but the applicants have now realised thatsurprisingly a much cheaper and simpler solution can be adopted.

SUMMARY OF THE INVENTION

Thus from one aspect the invention consists in apparatus for connectinga battery plate to a metal strap or post, including a mould having analigned set of posts or strap cavities, a molten metal feed duct forfeeding all the cavities in the set and extending adjacent thereto, aweir or weirs between the feed duct and the cavities, a feed passageextending below the feed duct for distributing molten lead to the ductand having a lead inlet characterised in that the lead inlet location isintermediate the ends of the set.

By feeding the lead intermediate the ends, the time lag between fillingis at once is reduced and by proper positioning of the location themould can be arranged such that those cavities to one side of thelocation are filled in equal time with those on the other side. Thus ina preferred embodiment the location is positioned such that the cavitieson either side of the location are filled in at least approximatelyequal time.

In most arrangements, where the cavities are symmetrical about a centreline, this will be achieved with a location which is at leastapproximately equidistant, measured along the duct, from the ends of theset. However, if the cavities are not of equal capacity or thecross-section of the duct on one side of the location is different tothe cross-section of the duct on the other side of the location someother position for the location may be preferred.

It will be understood, as indicated above, that simply by feedingintermediate the ends, a degree of improvement in terms of filling timecan be achieved over a feed duct which is fed solely from one end.

In general the feed passage may extend generally below the duct and maybe connected to the duct by at least one passage up which the lead canwell.

The passage may allow drain back of the lead to complete a cycle and themould may further include at least one body disposed in the feed duct soas to reduce the volume of that part of the feed duct which lies betweenthe lowest and highest level marks in the duct for lead in a cycle.

The invention also includes a mould for use in apparatus for connectingbattery plate to a metal strap or post having the features set outabove.

From another aspect the invention includes a mould for apparatus forconnecting a battery plate to a metal strap or post, the mould includingan aligned set of post or strap cavities, a molten metal feed duct forfeeding all the cavities in the set and extending adjacent thereto, aweir between the feed duct and the cavities, a feed passage extendingbelow the feed duct for supplying molten lead to the duct and forallowing drain back of the lead characterised in that there is at leastone body disposed in the feed duct so as to reduce the volume of thepart of the feed duct, which lies between the lowest and highest levelmarks in the duct for lead in a cycle.

From a further aspect the invention consists in a mould for connectingmetal strap or posts to respective battery plates for a plurality ofbatteries, the mould included aligned sets of post or strap cavities foreach battery, a molten metal feed duct for feeding all the cavities, alead feed for feeding lead to the feed duct and means for adjustinglocalised feed into the duct to obtain uniform cavity filling along theextent of the mould.

In any of the above cases bypass feeds may be provided along the feedduct for selectively providing localised lead flow.

Although the invention has been defined as above, it is to be understoodit includes any inventive combination of the features set out above orin the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be performed in various ways and a specific embodimentwill now be described, by way of example, with reference to theaccompanying drawings, in which,

FIG. 1 is a horizontal section through a mould, with the upper part ofthe mould showing the arrangement described in WO 94/16466, whilst thelower half of the drawing illustrates an embodiment of the invention;

FIG. 2 is a section along the line A-A in FIG. 1;

FIGS. 3 and 4 correspond to FIGS. 1 and 2 but include an optionaldisplacement bar;

FIG. 5 is a schematic cross-section through one cavity set showing thelead low level;

FIG. 6 is the corresponding view to FIG. 5 at the highest level leadmark; and

FIG. 7 is a plan view from above of a multiple battery mouldincorporating the bypass feeds of FIGS. 5 and 6.

DETAILED DESCRIPTION OF THE INVENTION

A mould is generally indicated at 10 and includes sets of mould cavities13, 14 which can be fed with lead, as described below, by weirs, some ofwhich are indicated at 15. The basic construction and operation of thesefeatures is identical to that described in British Patent No. 2023471Band the description of that patent is incorporated into thespecification for these purpose.

In the top half (the WO 94/16466) arrangement a pair of the passages 16,17 are fed with a source of lead indicated to feed respective halves ofthe set of moulds 13 by means of vertical passages such as indicated at19. As has been explained above this can lead to a time lag between thefilling of the cavities supplied by passage 16 as compared with thosesupplied by passage 17.

In contrast, as shown in the lower half of FIG. 1 and the left hand halfof FIG. 2, the lead is fed from passage 16 to passage 17 via an opening20 positioned intermediate the ends of the aligned cavities in the set14. The lead is then fed both left and right to well up passages 22 intoa duct 23, that feeds the cavities 14. As the location of opening 20 iscentral, the lead will feed into the left hand cavities 14 atapproximately the same time, as it flows into the right hand cavities,with the result that the timing of the dip of the lugs into the cavitiescan be optimised without any significant difficulties.

It will be understood that this solution is particularly efficacious.

As is generally well known moulds of this type work on what is known asthe tidal system whereby lead flows into the mould cavities 13, 14 to apoint of overflowing, normally under the operation of a pump, and thenthe pump is switched off and the excess lead in the mould drains backover the weir 15 and, mainly under gravity, then flows back to low levelor low tide mark in the feed duct, before starting the cycle again. Itis known to vary the overall volume which may be taken by the lead byincluding balance blocks, such as is indicated as 25 in FIG. 3, in orderto balance the volume which is being fed in conjunction with one set ofcavities, with the volume that is being fed in relation to another setof cavities but these do not significantly impinge on the volume of leadwhich exists between the low tide marks and the high tide marks duringthe cycle. The Applicants have appreciated that if they could reducethis latter volume, then they could significantly reduce the cycle time,because there is less lead to be pumped and, even more significantly,from a time point of view, there is less lead to be drawn back.

They therefore propose to provide a displacement bar 25 which can befitted to depend into the feed duct 23 to lie between the low level leadmark 28 and the high level lead mark 29. As can be seen in FIGS. 5 and 6the bar 25 thus occupies much of the volume between the low level andhigh level marks leaving the hatched volume 30 shown in FIG. 6 as theamount which needs to flow back towards the feed pipes 16, 17 over theweir 15.

Although the FIG. 5 structure would normally work as shown in FIG. 4with the feed pipe 16 feeding the feed pipe 17, as can be seen in FIG.5, optional connections direct from the feed pipe 16 to the duct 23,such as is shown at 16 a, can be provided to locally balance the flowinto the duct 23 and hence into the locally adjacent moulds.Conveniently connections 16 a are drilled along the length of the feedpipe 16 and then plugged as indicated in chain line 4 at 16 c. When themould is in situ a test run is carried out and the filling of theindividual cavities is inspected. If there is incomplete filling of anycavity then one or more adjacent plugs 16 c are removed to achieve theappropriate filling profile.

The Applicants have found that the ability to tune the localise flowlead, and in particular together with the enhanced lead flow achieved bythe intermediate main feed mentioned above, enables them to fillsimultaneously longitudinal aligned moulds for a plurality of batteries.This will hugely increase the productivity of any line incorporating themoulding apparatus.

FIG. 7 illustrates a mould for moulding the straps and posts for threebatteries as indicated as A, B and C.

1. A mould for apparatus for connecting a battery plate to a metal strapor post, the mould including an aligned set of post or strap cavities, amolten metal feed duct for feeding all the cavities in the set andextending adjacent thereto, a weir between the feed duct and thecavities, a feed passage extending below the feed duct for supplyingmolten lead to the duct and for allowing drain back of the leadcharacterised in that there is at lest one body disposed in the feedduct so as to reduce the volume of the part of the feed duct, which liesbetween the lowest and highest level in the duct for lead in a cycle.